Page 32 - Spring2010

phytase is produced by rumen microorganisms; of phytase—wheat contains fourteen times more phytase than rice and
monogastric animals also produce phytase, al- rye contains over twice as much phytase as wheat. Soaking or souring
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though far less. Mice produce thirty times more these grains, when freshly ground, in a warm environment will destroy
phytase than humans, so they can be quite all phytic acid. The high levels of phytase in rye explain why this grain is
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happy eating a raw whole grain diet. Data from preferred as a starter for sourdough breads.
experiments on phytic acid using mice and other Phytase is destroyed by steam heat at about 176 degrees Fahrenheit
rodents cannot be applied to humans. in ten minutes or less. In a wet solution, phytase is destroyed at 131-149
In general, humans do not produce enough degrees Fahrenheit. Thus heat processing, as in extrusion, will completely
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phytase to safely consume large quantities of destroy phytase—think of extruded all-bran cereal, very high in phytic
high-phytate foods on a regular basis. However, acid and all of its phytase destroyed by processing. Extruded cereals made
probiotic lactobacilli, and other species of the of bran and whole grains are a recipe for digestive problems and mineral
endogenous digestive microflora can produce deficiencies!
phytase. Thus, humans who have good intes- Phytase is present in small amounts in oats, but heat treating to produce
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tinal flora will have an easier time with foods commercial oatmeal renders it inactive.
containing phytic acid. Increased production of Even grinding a grain too quickly or at too high a temperature will
phytase by the gut microflora explains why some destroy phytase, as will freezing and long storage times. Fresh flour has a
volunteers can adjust to a high-phytate diet. higher content of phytase than does flour that has been stored. Traditional
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Sprouting activates phytase, thus reducing cultures generally grind their grain fresh before preparation. Weston Price
phytic acid. The use of sprouted grains will found that mice fed whole grain flours that were not freshly ground did
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reduce the quantity of phytic acids in animal not grow properly.
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feed, with no significant reduction of nutritional Cooking is not enough to reduce phytic acid—acid soaking before
value. 29 cooking is needed to activate phytase and let it do its work. For example,
Soaking grains and flour in an acid medium the elimination of phytic acid in quinoa requires fermenting or germinating
at very warm temperatures, as in the sourdough plus cooking (see Figure 3). In general, a combination of acidic soaking
process, also activates phytase and reduces or for considerable time and then cooking will reduce a significant portion
even eliminates phytic acid. of phytate in grains and legumes.
Before the advent of industrial agriculture,
farmers typically soaked crushed grain in hot THE PHYTATE THRESHOLD
water before feeding it to poultry and hogs. It appears that once the phytate level has been reduced, such that there
Today, feed manufacturers add phytase to grain is more available phosphorus than phytate in the grain, we have passed a
mixes to get better growth in animals. Com- critical point and the food becomes more beneficial than harmful. Reten-
mercial phytases are typically produced using tion of phosphorus decreases when phytate in the diet is 30-40 percent or
recombinant DNA technology. For example, a more of the total phosphorus.
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bacterial phytase gene has recently been inserted For best health, phytates should be lowered as much as possible,
into yeast for commercial production. ideally to 25 milligrams or less per 100 grams or to about .03 percent of
Not all grains contain enough phytase the phytate-containing food eaten. At this level, micronutrient losses are
to eliminate the phytate, even when properly minimized. (For phytate content of common foods as a percentage of dry
prepared. For example, corn, millet, oats and weight, see Figures 4 and 5.)
brown rice do not contain sufficient phytase to White rice and white bread are low-phytate foods because their bran
eliminate all the phytic acid they contain. On the and germ have been removed; of course, they are also devitalized and
other hand, wheat and rye contain high levels empty of vitamins and minerals. But the low phytate content of refined

FIGURE 3: QUINOA PHYTATE REDUCTION 34

PROCESS PHYTATE REDUCTION
Cooked for 25 minutes at 212 degrees F 15-20 percent
Soaked for 12-14 hours at 68 degrees F, then cooked 60-77 percent
Fermented with whey 16-18 hours at 86 degrees F, then cooked 82-88 percent
Soaked 12-14 hours, germinated 30 hours, lacto-fermented 16-18 hours, 97-98 percent
then cooked at 212 degrees F for 25 minutes
32 Wise Traditions SPRING 2010